This R24 application proposes development of integrated facilities to permit in vivo microscopic imaging in small animals using magnetic resonance microscopy and digital microradiography. MR microscopy will be extended in vivo to spatial resolution of 10 x 10 x 100 um using 2D selective rf pulses and surgically implanted rf coils. The potential for microscopy at 500 MHz will be explored through collaboration with colleagues at General Electric. Three dimensional vascular imaging will be developed using flow related enhancement and phase contrast techniques. Projection imaging will be implemented for time course studies and comparison to digital subtraction angiographic studies. These bulk flow measures will be complimented with exploration of diffusion and perfusion sequences. Further functional measures will be provided by chemical shift imaging to probe metabolic function over 0.1 cc volumes. Digital microradiography will be accomplished using proximity-focused microchannel plate intensifiers coupled to ccd arrays. These will be incorporated with microfocal spot xray tubes and digital acquisition to permit digital subtraction angiography in projection and stereo modes with spatial resolution to 25 um. Videodensitometry will permit time course studies of perfusion. Previous efforts to control motion in MR microscopy using scan synchronous respiration will be extended. Models of organ-specific pathology will be developed in lung, liver, kidney and brain. The facility will provide investigators the ability to serially study models of disease in small animals at microscopic resolution in an integrated fashion.